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1

Reports of the second All-Union conference on the chemistry of transplutonium elements (Dmitrovgrad, June 21-23, 1963)  

Energy Technology Data Exchange (ETDEWEB)

The nine papers presented at this conference cover the following topics: the systematization, condensed description, and prediction of sets of anion exchange extraction constants on the basis of their statistical computer treatment; characteristics and uses of solid extractants containing D2EHPA and TBP for separating the transplutonium elements; enrichment of americium 242m and americium 242 by the Szilard-Chalmers method; an x-ray diffraction pattern analysis for transplutonium compounds; the radiation chemistry of americium; and the effects of alpha irradiation on the behavior of americium in perchlorate solutions.

1987-05-01

2

The separation of trivalent actinides from lanthanides by dithiophosphinic acids from HNO_3 acid medium  

International Nuclear Information System (INIS)

The extraction of Am(III) and Eu(III) has been investigated using mixtures of synthesized aromatic dithiophosphinic acids (R_2PSSH) and tributylphosphate (TBP), trioctylphosphine oxide (TOPO) or tributylphosphine oxide (TBPO) in toluene from nitric acid (0.01-1.5 mol l"-"1). There was no detectable extraction when R_2PSSHs were used alone as extractants for either Am(III) or Eu(III) (D_A_m_,_E_u<10"-"4) under the experimental conditions used in this study. High separation factors (D_A_m/D_E_u>20) with D_A_m>1 were achieved in the nitric acid range 0.1-1 moll"-"1 by means of a synergistic mixture of bischlorodithiophosphinic acid with TBP, TOPO or TBPO. (orig.)

1998-06-12

3

Synthesis and characterization of new biopolymeric microcapsules containing DEHPA-?TOPO extractants for separation of uranium from phosphoric acid solutions  

British Library Electronic Table of Contents (United Kingdom)

A novel microcapsule adsorbent for separation of uranium from phosphoric acid solutions was developed by immobilizing the di(2-ethylhexyl) phosphoric acid-?trioctyl phosphine oxide extractants in the polymeric matrix of calcium alginate. Physical characterization of the microcapsules was accomplished by scanning electron microscopy and thermogravimetric techniques. Equilibrium experiments revealed that both ion exchange and solvent extraction mechanisms were involved in the adsorption of Formula Not Shown ions, but the latter prevailed in a wider range of acid concentration. According to the results of kinetics study, at low acidity level, the rate controlling step was slow chemical reaction of Formula Not Shown ions with the microdroplets of extractant, whereas it changed to intraparticle...

2011-01-01

4

Efficient Global Optimization Under Conditions of Noise and Uncertainty - A Multi-Model Multi-Grid Windowing Approach  

Energy Technology Data Exchange (ETDEWEB)

Incomplete convergence in numerical simulation such as computational physics simulations and/or Monte Carlo simulations can enter into the calculation of the objective function in an optimization problem, producing noise, bias, and topo- graphical inaccuracy in the objective function. These affect accuracy and convergence rate in the optimization problem. This paper is concerned with global searching of a diverse parameter space, graduating to accelerated local convergence to a (hopefully) global optimum, in a framework that acknowledges convergence uncertainty and manages model resolu- tion to efficiently reduce uncertainty in the final optimum. In its own right, the global-to-local optimization engine employed here (devised for noise tolerance) performs better than other classical and contemporary optimization approaches tried individually and in combination on the "industrial" test problem to be presented.

1999-05-18

5

Spectrophotometric studies on the formation of adducts involved in synergistic extraction of uranium (IV) by mixtures of HTTA and neutral donors  

International Nuclear Information System (INIS)

Adduct formation between U(TTA)_4 and several neutral donor (S) was investigated by utilizing the changes in the absorption spectra of U(IV) resulting from the addition of neutral donors to a solution of U(TTA)_4. All the donors used in the present work from 1:1 adducts with U(TTA)_4. From the spectral changes, the equilibrium constants #beta#sub(AB) for the adduct formation reaction viz U(TTA)_4 S reversible U(TTA)_4.S were calculated for a few neutral donors. The log #beta#sub(AB) values obtained in benzene medium, are :TOPO (6.23), TBPO (6.13), TPPO (4.72), DBBP(4.04) TBP(3.04), TIOTP(1.27) and MIBK(-0.10) and a value of 3.98 for TOPO in chloroform medium. The adduct formation was found to result in increasing the coordination number of U(IV) from 8 in U(TTA)_4 to 9 in the adducts it forms with the neutral donors. Similar absorption spectral studies with U(DBM)_4 revealed that it forms much weaker adducts than the corresponding ones with ...

1979-01-01

6

Bronchoalveolar lavage in systemic sclerosis with lung involvement: role and correlations with functional, radiological and scintigraphic parameters  

British Library Electronic Table of Contents (United Kingdom)

To evaluate the role and the prognostic value of bronchoalveolar lavage (BAL) in scleroderma patients with interstitial lung disease. We reviewed the records of 79 patients with systemic sclerosis (SSc) who had dyspnea and pulmonary involvement and underwent BAL study. Sixty-two patients were prospectively followed up for 12?36?months and re-evaluated by pulmonary function tests (PFTs). Seventy-nine SSc patients were enrolled (71 F and 8?M), 55 with limited and 24 with a diffuse form; mean age 55???13?years; mean disease duration 55.2???59?months. All patients were ANA positive, of these 30 were anti-topoisomerase-1 positive (anti-Topo1) and 22 were anti-centromere positive (ACA). Thirty-one patients had alveolitis (39.2%) that was neutrophilic in 12 patients, eosinophilic in 3 and mixed (...

2011-01-01

7

XAFS studies of nanocomposite systems  

Science.gov (United States)

Nanosized particles are important because of their unique properties, different from the bulk, which leads to their enhanced catalytic, photocatalytic and electronic properties. This work has dealt with three different nanoparticle systems in the context of three different aspects of nanoparticle properties: (a) photocatalytis (TiO2/metal) system, (b) luminescence (CdSe) (c) alloying (Pt-Ag and Pd-Ag). The initial photocatalytic enhancement obtained by adding noble metal on semiconductor nanoparticles, degrades as fast as in 15 minutes and questions their long-term performance. XANES measurements on such irradiated systems like TiO2/Au, TiO2/Pt, TiO2/Ir indicates a positive oxidation state of these noble metals which renders them as recombination centers for photo-excited electrons and explains the decreased photocurrent. The oxidation is caused by holes. The EXAFS results also indicate a change of the interfacial structure under the effect of UV-irradiation, thus affecting the ...